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c/coa·posted 2 years ago by u/noor_cardoso

help me understand batch, I have read the wiki twice

Question Cold Box ×4 Clean Column ×2

I have had 21 orders now and I keep a table, so here is the honest summary rather than a vibe.

Material has been consistent. Communication has not. Shipping has varied by about 20 days on nominally the same lane, which matters more in summer than in February.

The independent number came back 96.8% against a claimed 99.1%, which I read as agreement rather than a discrepancy — inter-lab variance on this assay is a point or two either way and treating one lab as ground truth is how people end up in pointless arguments with vendors.

Batch number is in the comments. Ask if you want the method.

11,858 up / 10,354 down53% upvoted22 commentsid 3gbwb219 Oct 2023

22 comments

15 in this archive, depth 5

best — the order this archive was captured in

u/liv_nkemelu116 points·2 years ago

Yeah, 96.8% area is not the problem, the missing impurity breakdown is the problem.

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u/wrong_network_w67 points·2 years ago
nope. mine was the opposite.
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u/dead_space_doug28 points·2 years ago

PDF metadata is checkable in fifteen seconds

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u/honest_syringe2442 points·2 years ago

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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u/zeynep_zielinski26 points·2 years ago

axis labels included, always

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u/anders_kuusela0 points·2 years ago

Not to be pedantic but purity and certificate of analysis are being used interchangeably and they are not interchangeable in real life.

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u/neha_erdogan40 points·2 years ago

Are you looking at area% or net peptide content? Different numbers.

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u/noor_cardosoOP58 points·2 years ago

chromatogram or it did not happen

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u/alcohol_aversion40 points·2 years ago

post the whole document, not the headline number

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u/freya_baptista10 points·2 years ago

Slight fix: the number was 98.7, not 98.9. Decimal point, but a fairly consequential one.

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u/mikkel_correia26 points·2 years ago

the batch number or it did not happen

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u/gallbladder_gary0 points·2 years ago

redact your own name, not the vendor's batch details

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u/spreadsheet_gremlindata17 points·2 years ago

The practical rule people converge on is 28 days at fridge temperature after first puncture, and that comes from the preservative, not the peptide.

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u/sofia_ferreira28 points·2 years ago

Strongly agree. Mass% and area% are answering different questions on the same document.

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u/teodor_jansen10 points·2 years ago·edited

PDF metadata is checkable in fifteen seconds

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About c/coa

How to read a certificate of analysis and what it does and does not tell you. Area% versus mass%, identity versus quantity, water content, related substances, acetate counterions, and the difference between a vendor-supplied COA and an independent test on the vial you actually received.

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c/coa rules
  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
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